Multiple Myeloma Plasmacytoid Infiltration of the Gallbladder Presenting as Acute Cholecystitis.

Secondary distal plasmacytoma that arise from multiple myeloma is a common hematological malignancy that manifests in later stages of the disease. These plasmacytomas are known to cause extensive systemic organ damage. When extramedullary plasmacytomas reach the gallbladder or biliary ducts, expansion can mimic acute acalculous cholecystitis or cholangiocarcinoma. We report a case of a 56-year-old female with a history of aggressive course IgA κ chain multiple myeloma who presented with right upper quadrant abdominal pain with nausea and vomiting for one week duration. Her laboratory panel revealed liver function tests consistent with gallbladder etiology. Abdominal ultrasound and CT showed no evidence of cholelithiasis precluding to acute acalculous cholecystitis. Initial medical management did not show any improvement. A robotic cholecystectomy was performed, and a pathology review of the specimen found a neoplastic stricture of the gallbladder fundus, the histological evaluation of which revealed plasmacytoid cells originating from her primary multiple myeloma diagnosis. The patient's condition declined following surgery, postoperative presentation included metastatic liver thrombosis mimicking cholangiocarcinoma and the patient later expired with palliative care.